A bottom surface with an adhesion surface including a plurality of micro-protrusions, or an adhesive adhered to the bottom surface a pressure monitoring device configured to measure intraocular pressure of an eye and generate a signal representing the measured pressure and a transmitter configured to transmit the signal. The bottom surface is arranged to secure the sensor to: an outer surface of a conjunctiva for the eye without penetrating the conjunctiva or an outer surface of a sclera for the eye without penetrating the sclera.
